Method of making leather balls



March 17, 1936. T, R DDEL 2,034,249

METHOD OF MAKING LEATHER BALLS Z? JO/m 731C161! 'Marzh 17, 1936. J. T. RIDDELL. 2,034,249

METHOD OF MAKING LEATHER BALLS F'iled Dec. 18, 1953 2 Sheets-Sheet 2 Iii Patented Mar. 17, 1936 UNITED STATES TEN T OFF-1C E 1 Claim.

This invention relates to the manufacture of leather articles and particularly playing balls provided with leather casings that are inflated for use, as forexample, basket balls, footballs, socker balls, volley balls, and the like.

One of the principal ends that is sought in the manufacture of playing balls is to obtain accurate conformity to a predetermined size and shape, and to insure that the balls will retain such size and shape without distortion over a long period of use in play.

The main object of this invention is to provide a method of treating leather and forming it into a ball casing having exact conformity to a predetermined standard shape, and of such uniform texture and condition as to eliminate so far-as possible any unintended stretching of the casing and any unevenness in theperipheral contour that might result from age and abuses to which the ball might be subjected in play; and particularly to provide a 'method of manufacture whereby the leather may be uniformly stretched and per- -manently set to its final spheroidalform with a minimum of possible inherent structural conditions that might ultimately give rise to deviation {from the desired shape-forthe play for Whichit is designed.

A specific embodiment of my improved method andcertain apparatus for carrying it out are shown in the accompanying drawings in which:

Figure 1 is a detail showing the shape of the leather blanks out of which the ball is to be made.

Fig. 2 is a fragmentary side elevation of a machine which is employed for stretching and shaping the leather sheets over the form blocks.

Fig. 3 is a side View showing the form block and leather sheet in their relation to a pressure templet that is employed for clamping down the leather sheet and guiding the trimming step of the process.

Fig. 4 is a perspective view of the ball segment after it has been treated by the machine shown in Figure 2 and trimmed to shape with the templet shown in Figure 3.

Fig. 5 illustrates how one panel of each set is folded, slitted and perforated to provide the lacing slit through which the bladder is inserted.

Fig. 6 is a plan view of this panel when unfolded.

Fig. '7 is a perspective view showing a set of six of the panels assembled with their outer or grain sides in, as they appear in hexahedral form after their marginal edges are sewn together.

Fig. 8 is a perspective view of the finished infiated ball.

Fig. 9 is a sectional detail of the mold with the ballin place ready for thefinal operation of inflation and stretching of the ball casing Withinthe -mold.

In the drawings, I have illustrated the principal steps employed in the manufacture of a spherical .5 ball having its surface subdivided .to correspond with the spherical areas that would subtend an imaginarycube having its cornersin the surface of the ball, but it will be readily seen that the -method of manufacturing,to be hereinafter de- .10 scribed, is equally applicable to other shapes of balls and to other arrangements of the surface segments.

1 In themanufacture of -high grade leather balls .great' care must be taken to-select leather ofthe desired thickness and which is uniform in thickness and texture throughout. In making a ball of the type shown in Figure'8, the leather is out up into pieces ll] of the four-sided form shown in :Figure 1 and of dimensions predetermined by experience. These are first assembled in right and left pairs sothat when sewn together on their longer curved edges l I, they will form units roughly approximatingthe shape as shown in Figure A of the;ballcasing sections.

In thestretching machine illustrated in Figure -;2, which is'described in greater detail in my copendjng application, Serial No. 702,918,; filed-of even date herewith and issued as Patent No. 2,005,804, June 25, 1935, a form block l2 conforming approximately to the spherical contour of the ball, but of a size slightly smaller than the finished ball, is mounted upon a crosshead [3.

The unit casing panel I4, consisting preferably of two of the parts It sewn together at their corresponding edges H, is thoroughly soaked in water and laid over the form block l2 with the edges of the seam l5 lying in a groove l6 cut in the surface of the form as appears in Figure 3. The clamps ll of a series of radiating stretcher members l8 are then attached to the marginal edges of the sheet I4 at substantially equal distances apart and the stretcher members l8 are adjusted by means of the turnbuckles l9 so that each stretcher member will exert equal tension on the sheet of leather. Incorporated in each of the stretcher members I8 is a spring balance 20 by means of which the stretching tension is indicated. The turnbuckles are adjusted until each of the indicators 2! of the spring balances stands opposite the same graduation on its respective scale.

The crosshead I3 is then raised by means of a jack which forms part of the machine fragmentarily illustrated in Figure 2 until a certain predetermined maximum strain is applied to the leather and if there is any lack of uniformity in the indications of the spring balances, these may be individually adjusted by the turnbuckles to again bring them all to the same indication.

The margins of the leather sheet are then secured to the blocks by means of a series of tacks 22 after which the clamps are released and the block l2 with its attached sheet of leather is set aside to dry and a new block 12 is placed on the crosshead l3 and this part of the operation is repeated.

After these. preformed leather panels have be-- come thoroughly dry, the tacks 22 are removed and the blocks, with the leather still in place thereon, are set in a press, the upper member of which is shaped so as to clamp the leather tightly against the surface of the block I! and the marginal edges of which are shaped to form a template to guide the trimming of the leather to the exact shape shown in Figures 4 and 6 which is the shape of the casing panel of the finished ball with a uniform marginal excess to form the seams between panels.

The next step in the process is to take one of the panels of each set of six and fold it on the middle seam, bringing the grain sides thereof together as in Figure 5. A portion of the seam margin is then trimmed away to form the slit 23, and the valve stem aperture 24; and in the same operation the row of perforations 25 is made for the lacing cords.

The six panels of the set are then tied together at their corners with their grain sides opposed and their marginal edges are sewn together,- preferably by machine, to complete the hexahedral assembly shown in Figure 7.

The next step inthe operation is to cut the threads of the seams 26 at each end of the slit 23 and invert the parts through this slit so as to bring the grain side out. The seams 26 are then resewn by hand, a. bladder 21, Figure 9, is

then inserted through the slit 23 and the ball is partly inflated and placed in the mold 28, where under a pressure of approximately H pounds it is given a final stretching and. brought to its exact spherical or other desired form as determined by the form of the cavity in the mold 28.

After being left in the mold under this pressure for a sufficient time, to permanently establish this form, approximately one hour, its internal pressure is reducedto 13 pounds, the normal playing pressure, and it is ready for the market.

This invention is a development from and an improvement upon the methods of manufacture in an accurate mold, I am able to obtain under mass production methods of factory operation a maximum degree of excellence and uniformity of 7 product.

While I have particularly described my invention with respect to playing balls, it will be understood that the procedure described may also be applicable to the manufacture of other inflatable products of leather or analogous fibrous material.

The term leather as herein used is intended to include in addition to tanned skins, any analogous sheet material such as artificial leather and certain fabrics that might be substituted therefor.

Although but one'specific embodiment of the invention has been herein shown and described, it will be understood that numerous details of the subject matter disclosed may be altered or omitted without departing from the spirit of the invention as defined by the following claim.

I claim:

The method of manufacture of leather balls which consists of Wetting a sheet of leather, laying the same on a spheroidal form, applying uniform tensional strains on said sheet at a plurality of points spaced about the margins thereof and in directions radiating substantially from a common center, increasing the said strains uniformly and simultaneously to attain a desired stretch in said sheet of leather, and allowing the leather to dry under such strains.

JOHN T. RIDDELL. 

